Technical Abstract:
More than 76 million citizens are sickened each year by consuming foods contaminated with pathogenic bacteria. The most important food-borne pathogen in cattle remains E. coli O157:H7 and its closely related enterohemorrhagic E. coli strains (EHEC) cause more than 90,000 illnesses each year in the US at a cost of more than $1 billion USD. In-plant pathogen reduction strategies are effective at improving food safety, but do not stop all human illnesses caused by E. coli O157:H7. Humans can be indirectly infected by E. coli O157:H7 through runoff from farms that enter the water supply and are consumed on crops (such as spinach or lettuce) or directly via drinking water. Furthermore, human E. coli O157:H7 illnesses result from direct animal or fecal contact at petting zoos and open farms. Thus, if we can reduce E. coli O157:H7 populations in cattle while they are still on the farm, then we can reduce subsequent human illnesses. The microbial ecology and diversity of the intestinal tract of cattle is a resource that can be exploited to reduce food-borne pathogen populations in the gut via natural competitive mechanisms. The ecology of the intestinal tract is very similar to that of the larger world and follows similar principles of “survival of the fittest.” Methods to be discussed in this presentation include: probiotics and competitive exclusion, bacteriophage, dietary changes, bacterial physiology, and antimicrobials. The implementation of several of these intervention strategies in tandem could introduce “multiple hurdles” to the entry of food-borne pathogenic bacteria to humans. Further research is needed to determine the synergistic potential of these strategies that utilize the ecology of the gut against E. coli O157:H7.